1. Field of the Invention
Exemplary embodiments of the present invention relate to a receiver, a generator, an error-averager, and a determiner, and methods for the same.
2. Description of the Conventional Art
Viewers may buy television receivers, which may have digital television (DTV) receivers and/or digital set-top boxes to view images provided by digital broadcasting.
Conventional analog broadcasting signals may include, for example, national television system committee (NTSC) signals, phase alternation by line system (PAL) signals, and sequential couleur a memoire (SECAM) signals. DTV signals may include 8-level vestigial side band (VSB) signals, which may be defined by, for example, the advanced television system committee (ATSC). Receivers, which may have DTV receivers and digital set-top boxes may process analog and digital broadcasting signals. Digital set-top boxes alone may not receive analog broadcasting signals.
Signals, for example, DTV broadcasting signals, satellite broadcasting signals, cable TV broadcasting signals, and wireless local area network (WLAN) signals may be used for broadcasting and it may be difficult to allocate other broadcast frequency bands. Analog and digital broadcasting signals may be allocated to a co-channel, for example, an ultra high frequency (UHF) channel or a very high frequency (VHF) channel and transmitted through the co-channel. If an analog broadcasting signal, for example, an NTSC signal and a digital broadcasting signal exist in a co-channel, when an analog television receiver demodulates an analog broadcasting signal into a display signal, the digital broadcasting signal may act as a smaller noise component, and the analog broadcasting signal may be received. When a DTV receiver demodulates a digital broadcasting signal to a display signal, the level of co-channel interference with an NTSC signal may be higher and the digital broadcasting signal may not be received.
FIG. 1 is a block diagram of a conventional digital (e.g., DTV) receiver 100. Referring to FIG. 1, the DTV receiver 100 may include a tuner 101, a VSB demodulator 102, a sync and timing recovery unit 103, a 12 symbol delay comb filter 104, which may remove an NTSC signal, an equalizer 105, an 8-state trellis decoder 106, a de-interleaver 107, and a Reed-Solomon (RS) decoder 108. In the output of the 12 symbol delay comb-filter 104, deep spectral nulls may be introduced at the locations of video, chroma, and audio carriers of, for example, an NTSC signal. The power of the NTSC signal, which may pass through the 12 symbol delay comb-filter 104, may be reduced (e.g., significantly reduced). A VSB signal, which may pass through the 12 symbol comb-filter 104, may be output as a 15-level constellation, and the 8-state trellis decoder 106 may detect the 15-level constellation. The DTV receiver 100, which may cancel co-channel (e.g., NTSC co-channel) interference may improve performance when a signal-to-noise ratio (SNR) of a received signal may be greater than, for example, 20 dB. When the SNR of the received signal is less than 19 dB, the performance of the DTV receiver 100 may degrade (e.g., significantly degrade). The DTV receiver 100 may use a switching scheme for detecting and removing, for example, the NTSC signal.
FIG. 2 is a block diagram of another conventional DTV receiver 200. Referring to FIG. 2, the DTV receiver 200 may include a tuner 201, a VSB demodulator 202, a sync and timing recovery unit 203, a decision feedback equalizer (DFE) 204, a 4-state trellis decoder 205, a de-interleaver 206, and an RS decoder 207. An output of the 4-state trellis decoder 205, a trellis-coded modulation (TCM) decoder, may feed back to the DFE 204 and the DFE 204 may equalize spectral nulls. The performance of the DFE 204 may not degrade in the additive white Gaussian noise (AWGN) channel and the DFE 204 need not detect and remove the NTSC signal using a switching scheme. The DTV receiver 200 may reduce NTSC co-channel interference using the DFE 204. The DFE 204 may partially equalize co-channel interference due to, for example, time-varying characteristics of the NTSC signal. Noise, which may be caused by co-channel interference, may need to be removed from an output signal of the DFE 204. Noise may be at rising and/or falling edges of an NTSC line synchronous signal. The NTSC line synchronous signal may be a clock signal, which may have an NTSC horizontal scan rate. According to, for example, the Advanced Television System Committee High Definition Television (ATSC-HDTV) standard, the cycle of the NTSC line synchronous signal may be equal, or substantially equal, to 684 symbols of an 8-VSB signal.